Dynamic changes of ICA-derived EEG functional connectivity in the resting state.

An emerging issue in neuroscience is how to identify baseline state(s) and accompanying networks termed "resting state networks" (RSNs). Although independent component analysis (ICA) in fMRI studies has elucidated synchronous spatiotemporal patterns during cognitive tasks, less is known about the changes in EEG functional connectivity between eyes closed (EC) and eyes open (EO) states, two traditionally used baseline indices. Here we investigated healthy subjects (n = 27) in EC and EO employing a four-step analytic approach to the EEG: (1) group ICA to extract independent components (ICs), (2) standardized low-resolution tomography analysis (sLORETA) for cortical source localization of IC network nodes, followed by (3) graph theory for functional connectivity estimation of epochwise IC band-power, and (4) circumscribing IC similarity measures via hierarchical cluster analysis and multidimensional scaling (MDS). Our proof-of-concept results on alpha-band power demonstrate five statistically clustered groups with frontal, central, parietal, occipitotemporal, and occipital sources. Importantly, during EO compared with EC, graph analyses revealed two salient functional networks with frontoparietal connectivity: a more medial network with nodes in the mPFC/precuneus which overlaps with the "default-mode network" (DMN), and a more lateralized network comprising the middle frontal gyrus and inferior parietal lobule, coinciding with the "dorsal attention network" (DAN). Furthermore, a separate MDS analysis of ICs supported the emergence of a pattern of increased proximity (shared information) between frontal and parietal clusters specifically for the EO state. We propose that the disclosed component groups and their source-derived EEG functional connectivity maps may be a valuable method for elucidating direct neuronal (electrophysiological) RSNs in healthy people and those suffering from brain disorders.

Endogenous control of waking brain rhythms induces neuroplasticity in humans.

This study explores the possibility of noninvasively inducing long-term changes in human corticomotor excitability by means of a brain-computer interface, which enables users to exert internal control over the cortical rhythms recorded from the scalp. We demonstrate that self-regulation of electroencephalogram rhythms in quietly sitting, naive humans significantly affects the subsequent corticomotor response to transcranial magnetic stimulation, producing durable and correlated changes in neurotransmission. Specifically, we show that the intrinsic suppression of alpha cortical rhythms can in itself produce robust increases in corticospinal excitability and decreases in intracortical inhibition of up to 150%, which last for at least 20 min. Our observations may have important implications for therapies of brain disorders associated with abnormal cortical rhythms, and support the use of electroencephalogram-based neurofeedback as a noninvasive tool for establishing a causal link between rhythmic cortical activities and their functions.

Optimizing microsurgical skills with EEG neurofeedback.

BACKGROUND: By enabling individuals to self-regulate their brainwave activity in the field of optimal performance in healthy individuals, neurofeedback has been found to improve cognitive and artistic performance. Here we assessed whether two distinct EEG neurofeedback protocols could develop surgical skill, given the important role this skill plays in medicine. RESULTS: National Health Service trainee ophthalmic microsurgeons (N = 20) were randomly assigned to either Sensory Motor Rhythm-Theta (SMR) or Alpha-Theta (AT) groups, a randomized subset of which were also part of a wait-list 'no-treatment' control group (N = 8). Neurofeedback groups received eight 30-minute sessions of EEG training. Pre-post assessment included a skills lab surgical procedure with timed measures and expert ratings from video-recordings by consultant surgeons, together with state/trait anxiety self-reports. SMR training demonstrated advantages absent in the control group, with improvements in surgical skill according to 1) the expert ratings: overall technique (d = 0.6, p < 0.03) and suture task (d = 0.9, p < 0.02) (judges' intraclass correlation coefficient = 0.85); and 2) with overall time on task (d = 0.5, p = 0.02), while everyday anxiety (trait) decreased (d = 0.5, p < 0.02). Importantly the decrease in surgical task time was strongly associated with SMR EEG training changes (p < 0.01), especially with continued reduction of theta (4-7 Hz) power. AT training produced marginal improvements in technique and overall performance time, which were accompanied by a standard error indicative of large individual differences. Notwithstanding, successful within session elevation of the theta-alpha ratio correlated positively with improvements in overall technique (r = 0.64, p = 0.047). CONCLUSION: SMR-Theta neurofeedback training provided significant improvement in surgical technique whilst considerably reducing time on task by 26%. There was also evidence that AT training marginally reduced total surgery time, despite suboptimal training efficacies. Overall, the data set provides encouraging evidence of optimised learning of a complex medical specialty via neurofeedback training.

Neurofeedback of SMR and Beta1 Frequencies: An Investigation of Learning Indices and Frequency-Specific Effects.

Despite evidence that Sensorimotor Rhythm (SMR) and beta1 neurofeedback have distinct cognitive enhancement effects, it remains unclear whether their amplitudes can be independently enhanced. Furthermore, demands for top-down attention control, postural restraint and maintenance of cognitive set processes, all requiring low-beta frequencies, might masquerade as learning and confound interpretation. The feasibility of selectively enhancing SMR and beta1 amplitudes was investigated with the addition of a random frequency control condition that also requires the potentially confounding cognitive processes. A comprehensive approach to assessing neurofeedback learning was undertaken through the calculation of learning indices within- and across-session and pre-to-post baseline. Herein we provide the first demonstration of beta1 within-session amplitude learning that was not attributable to extraneous cognitive processes, for it was not found with random frequency training. On the other hand, within-session SMR learning might have been obscured by high interindividual variability and methodological limitations such as the type of feedback screen, the insufficient number of sessions, and the exclusion of simultaneous theta and high-beta inhibition. Interestingly, SMR and beta1 amplitude increased across sessions in the three groups suggesting unspecific effects of neurofeedback in the low beta frequency band. Moreover, there was no clear evidence of frequency specificity associated with either SMR or beta1 training. Some methodological limitations may underpin the divergent results with previous studies.

Short-term Beneficial Effects of 12 Sessions of Neurofeedback on Avoidant Personality Accentuation in the Treatment of Alcohol Use Disorder.

This study evaluated the effects of alpha/theta neurofeedback on Clinical Personality Accentuations in individuals with alcohol use disorder. Twenty-five males were investigated using a pre-test/post-test design with a waiting-list control group. Participants were randomly assigned either to an experimental group (n = 13) receiving 12 sessions of neurofeedback twice a week as a treatment adjunct over a period of 6 weeks, or to a control group (n = 12) receiving treatment as usual. The Inventory of Clinical Personality Accentuations and the NEO-Five-Factor Inventory were applied at pre- and post-test. The neurofeedback protocol focused on enhancement of the EEG alpha (8-12 Hz) and theta (4-7 Hz) and used a visual feedback paradigm. Analyses of covariance showed improvements in Avoidant Personality Accentuation within the experimental group. Our data suggest that 12 sessions of this neurofeedback intervention might be effective in reducing avoidant and stress-related personality traits in patients with alcohol use disorder.

Event-related brain potential correlates of human auditory sensory memory-trace formation.

The event-related potential (ERP) component mismatch negativity (MMN) is a neural marker of human echoic memory. MMN is elicited by deviant sounds embedded in a stream of frequent standards, reflecting the deviation from an inferred memory trace of the standard stimulus. The strength of this memory trace is thought to be proportional to the number of repetitions of the standard tone, visible as the progressive enhancement of MMN with number of repetitions (MMN memory-trace effect). However, no direct ERP correlates of the formation of echoic memory traces are currently known. This study set out to investigate changes in ERPs to different numbers of repetitions of standards, delivered in a roving-stimulus paradigm in which the frequency of the standard stimulus changed randomly between stimulus trains. Normal healthy volunteers (n = 40) were engaged in two experimental conditions: during passive listening and while actively discriminating changes in tone frequency. As predicted, MMN increased with increasing number of standards. However, this MMN memory-trace effect was caused mainly by enhancement with stimulus repetition of a slow positive wave from 50 to 250 ms poststimulus in the standard ERP, which is termed here "repetition positivity" (RP). This RP was recorded from frontocentral electrodes when participants were passively listening to or actively discriminating changes in tone frequency. RP may represent a human ERP correlate of rapid and stimulus-specific adaptation, a candidate neuronal mechanism underlying sensory memory formation in the auditory cortex.

Investigating evoked and induced electroencephalogram activity in task-related alpha power increases during an internally directed attention task.

This study sought to explore whether the so-called 'paradoxical' task-related increases in the alpha bandwidth of the human electroencephalogram result from increases in evoked (phase locked), as opposed to induced (non-phase locked), activity. The electroencephalograms of 18 participants were recorded while they engaged in both auditory sensory-intake tasks (listening to randomly generated 'tunes') and internally directed attention tasks (imagining the same randomly generated tunes) matched for auditory input. Measures of evoked (phase locked) and induced (non-phase locked) activity were compared between tasks. Increases in induced alpha power were found during internal attention. No experimental effects were observed for evoked activity. These results are not entirely consistent with proposals that 'paradoxical' alpha indexes the evoked inhibition of task irrelevant processing.

Relaxation strategies and enhancement of hypnotic susceptibility: EEG neurofeedback, progressive muscle relaxation and self-hypnosis.

Hypnosis has been shown to be efficacious in a range of clinical conditions, including the management of chronic pain. However, not all individuals are able to enter a hypnotic state, thereby limiting the clinical utility of this technique. We sought to determine whether hypnotic susceptibility could be increased using three methods thought to facilitate relaxation, with particular interest in an EEG neurofeedback protocol which elevated the theta to alpha ratio. This was compared with progressive muscle relaxation and self-hypnosis. Ten subjects with moderate levels of susceptibility (2-7/12) were randomly assigned to each condition and assessed for hypnotic susceptibility prior to and upon completion of 10 sessions of training. Hypnotic susceptibility increased post-training in all groups, providing further evidence that operant control over the theta/alpha ratio is possible, but contrary to our predictions, elevation of the theta/alpha ratio proved no more successful than the other interventions. Nonetheless, all three techniques successfully enhanced hypnotic susceptibility in over half of the participants (17/30), a similar incidence to that reported using other methods. As previously reported, the majority who were not susceptible to modification were at the lower levels of susceptibility, and the greater increases tended to occur in the more susceptible subjects. However, here enhancement was disclosed in some at low levels, and capability was found of reaching high levels, both features not typically reported. Further research is warranted.

The influence of 10 min of the Johrei healing method on laboratory stress.

OBJECTIVE: Johrei has been shown to decrease exam stress responses but its immediate effects have not been assessed. DESIGN: In a randomised, blinded, counter-balanced design, 33 medical students were asked to calculate mental arithmetic in the Paced Auditory Serial Addition Task (PASAT), which served as an acute stressor prior to two conditions, 10 min of Johrei or a control resting condition involving 10 min without Johrei in a cross-over trial; after each, saliva was collected and mood tested. SETTING: University EEG laboratory. INTERVENTION: Johrei, a non-touch healing method. MAIN OUTCOME MEASURES: Profile of mood states (POMS-Bi); state anxiety (STAI); salivary variables: cortisol, DHEA, IgA. RESULTS: Mood scores on 5/6 of the POMS-Bi subscales were slightly but significantly more positive in the Johrei condition. State anxiety was similarly decreased. IgA levels were unchanged but cortisol levels were found to be slightly but non-significantly lower after Johrei than after the control condition and DHEA levels slightly but non-significantly raised, with a negative correlation between cortisol and DHEA levels. CONCLUSIONS: This study gives some indication that Johrei can reduce negative mood and increase positive mood states after the acute effects of a laboratory stressor in comparison to a resting control condition.

The Effectiveness of Visual Short-Time Neurofeedback on Brain Activity and Clinical Characteristics in Alcohol Use Disorders: Practical Issues and Results.

The present study was carried out to examine the efficacy of alpha/theta neurofeedback (NF) with a new visual paradigm in a cohort of alcohol use disordered (AUD) patients (n = 25) treated in an Austrian therapeutic community center. The experimental study design focused on changes in absolute and relative resting EEG band power as well as in clinical variables, including depression (Beck Depresion Inventory [BDI-V]), psychiatric symptoms (Brief Symptom Inventory [BSI], coping (Freiburg Questionnaire on Coping with Illness [FKV-lis]), psychotherapy motivation (Therapy Motivation Questionnaire [FPTM-23]), sense of coherence (Sense of Coherence Scale [SOC-13]), posttraumatic growth (Posttraumatic Growth Inventory [PPR]), and alcohol cravings (Alcohol Craving Questionnaire [ACQ]). For measuring training effects, participants were randomly allocated to 2 groups: an experimental group (EG, n = 13) and a control group (CG, n = 12). Patients in EG received 12 sessions of visual NF training over a period of 6 weeks to enhance alpha (8-12 Hz) and theta (4-7 Hz) frequency band power in addition to the standard treatment program of the rehabilitation center. Participants in CG received no additional NF intervention. The multivariate analysis of covariance (MANCOVA) showed a change by trend in absolute alpha and theta power in the EG. Even though no MANCOVA effects were found in the clinical scales, AUD patients reported increasing control of their brain activity during the course of NF. However, changes in several clinical scales (BDI-V, BSI, FKV-lis, PPR) from pre- to posttest were observed only in the EG contrary to the CG. The findings of this pilot study provide first evidence for the practicality and effectiveness of visual short-term NF as an additive intervention in the therapeutic community.

The effects of alpha/theta neurofeedback on personality and mood.

Alpha/theta neurofeedback has been shown to be successful both in treating addictions and in enhancing artistry in music students. How its effects are mediated are not yet clear. The present study aimed to test the hypothesis that alpha/theta neurofeedback works inter alia by normalising extreme personality and raising feelings of well being. 12 participants with high scores for Withdrawal (as measured by the PSQ) were given either alpha/theta neurofeedback or mock feedback and their personality and mood were assessed. Withdrawal scores on the PSQ-80 were not found to change in either group but significant effects were found for the Profile Of Mood States (POMS), with real feedback producing higher overall scores than mock feedback (P = 0.056). Real feedback caused participants to feel significantly more energetic (P < 0.01) than did mock feedback. Sessions of real feedback made participants feel more composed (P < 0.01), agreeable (P < 0.01), elevated (P < 0.01) and confident (P < 0.05), whilst sessions of mock feedback made participants feel more tired (P < 0.05), yet composed (P < 0.01). These findings suggest that, whilst 9 sessions of alpha/theta neurofeedback was insufficient to change personality, improvements in mood may provide a partial explanation for the efficacy of alpha/theta neurofeedback.

Changes in mismatch negativity across pre-hypnosis, hypnosis and post-hypnosis conditions distinguish high from low hypnotic susceptibility groups.

The role of alterations in mismatch negativity (MMN) in hypnosis was examined by recording MMN of the auditory ERP at frontal (F3, Fz, and F4) and mastoid (M1 and M2) placements. Frontal MMN is believed to reflect activity in right anterior cortical generators, whereas MMN at mastoid leads reflects generators located bilaterally in the temporal auditory cortex. MMN recordings were obtained in 11 low and 12 high hypnotically susceptible participants in three successive blocks; pre-hypnosis, hypnosis and post-hypnosis. Frontal (but not temporal) MMN showed a significant quadratic trend across testing conditions. It increased during hypnosis and then dropped post-hypnosis for both susceptibility groups. Linear trends for frontal and temporal MMN showed directly opposite patterns of change in the interaction between hypnotic susceptibility and testing blocks. Frontal MMN built up linearly over the test blocks in high relative to low susceptibility participants. Temporal MMN showed the reverse pattern and increased linearly across test conditions in those with low relative to high hypnotic susceptibility.

The influence of anxiety on electrodermal responses to distractors.

Contrary to classical expectation, anxiety has been repeatedly observed to be associated with reduced electrodermal activity. This could be the result of successful coping. In line with this interpretation, high-trait anxious individuals performing moderately arousing tasks were expected to manifest a reduced responding to distractors, since this is an adaptive outcome. High- and low-trait anxious participants had to perform a visual search task in a low-stress context. Unrelated neutral and emotional auditory words served as distractors. As a control, neutral and emotional words were also delivered in a no task condition. Skin conductance responses (SCRs) were greater during the task than during the control phase, but in the high anxious group, this increase in SCRs was smaller following emotional distractors than following neutral ones. Moreover, SCRs to both types of words habituated, but the results suggested that only the low-trait anxious participants presented the classical slowing of SCRs habituation when performing the task. All these data are interpreted as an illustration of a resource-based electrodermal inhibition in the high-trait anxious participants. It sustains the idea that mild to moderate anxiety may increase the mastery of situations.

Ecological validity of neurofeedback: modulation of slow wave EEG enhances musical performance.

Biofeedback-assisted modulation of electrocortical activity has been established to have intrinsic clinical benefits and has been shown to improve cognitive performance in healthy humans. In order to further investigate the pedagogic relevance of electroencephalograph (EEG) biofeedback (neurofeedback) for enhancing normal function, a series of investigations assessed the training's impact on an ecologically valid real-life behavioural performance measure: music performance under stressful conditions in conservatoire students. In a pilot study, single-blind expert ratings documented improvements in musical performance in a student group that received training on attention and relaxation related neurofeedback protocols, and improvements were highly correlated with learning to progressively raise theta (5-8 Hz) over alpha (8-11 Hz) band amplitudes. These findings were replicated in a second experiment where an alpha/theta training group displayed significant performance enhancement not found with other neurofeedback training protocols or in alternative interventions, including the widely applied Alexander technique.

The impact of self-hypnosis and Johrei on lymphocyte subpopulations at exam time: a controlled study.

In a prospective randomised controlled trial, 48 students were randomly assigned to stress reduction training before exams with self-hypnosis, Johrei or a mock neurofeedback relaxation control. Peripheral blood lymphocyte subpopulations and self-reported stress (Perceived Stress Scale) were measured before training and 1-2 months later as exams approached. Absolute number and percentages of CD3(+)CD4(+) and CD3(+)CD8(+) T lymphocytes, CD3(-)CD56(+) Natural Killer cells (NK cells) and NK cell cytotoxic activity was measured from venous blood. Stressed participants showed small but significant declines in both CD3(-)CD56(+) NK cell percentages and NK cell cytotoxic activity levels while CD3(+)CD4(+) T cell percentages increased, changes supported by correlations with perceived stress. The effects of stress were moderated in those who learned Johrei at exam time; 11/12 showed increases in CD3(-)CD56(+) NK cell percentages with decreased percentages of CD3(+)CD4(+) T cells, effects not seen in the relaxation control group. Stress was also buffered in those who learned and practised self-hypnosis in whom CD3(-)CD56(+) NK cell and CD3(+)CD4(+) T cell levels were maintained, and whose CD3(+)CD8(+) T cell percentages, shown previously to decline with exams, increased. The results compliment beneficial effects on mood of self-hypnosis and Johrei. The results are in keeping with beneficial influences of self-hypnosis and provide the first evidence of the suggestive value of the Japanese Johrei procedure for stress reduction, which clearly warrants further investigation.

Theory, methods and new directions in the psychophysiology of the schizophrenic process and schizotypy.

Theoretical and methodological issues in the psychophysiology of the schizophrenic process are reviewed. These include the importance of schizotypy with its compensatory abilities as well as deficits for elucidating the processes of development and prevention of schizophrenia. The importance of individual differences, syndromes and single case studies. The recognition that this is a dynamic and fluctuating illness and hence the relevance of functional neurophysiology, including the role of imbalances in hemispheric activation in ontogeny, developmental course, expression of symptoms, the effects of neuroleptics and recovery process, and the influence of stress a precipitant of breakdown. The role of thalamo-cortical activation systems. The particular value of electrocortical measures including the interrelations of electroencephalographic rhythms throughout the spectrum, and relations of gamma, dynamic core neuronal complexity, connectivity and sensory gating with experiences of unreality and disturbances of consciousness.

Pain perception, hypnosis and 40 Hz oscillations.

A number of brain regions are associated with the subjective experience of pain. This study adds to our understanding of the neural mechanisms involved in pain by considering the relation between cortical oscillations in response to pain, with and without hypnosis and hypnotic analgesia, and the subjective experience of pain. Thirty-three subjects' neural responses (EEG) were measured during the 40-540 ms period following phasic electrical stimulations to the right hand, under control and hypnosis conditions. Resultant FFT amplitudes for frequencies ranging from 8 to 100 Hz were computed. These were grouped into 7 scalp topographies, and for each frequency, relations between these topographies and pain ratings, performance and stimulus intensity measures were assessed. Gamma activity (32-100 Hz) over prefrontal scalp sites predicted subject pain ratings in the control condition (r=0.50, P=0.004), and no other frequency/topography combination did. This relation was present in both high and low hypnotisable subjects and was independent of performance and stimulus intensity measures. This relation was unchanged by hypnosis in the low hypnotisable subjects but was not present in the highs during hypnosis, suggesting that hypnosis interferes with this pain/gamma relation. This study provides evidence for the role of gamma oscillations in the subjective experience of pain. Further, it is in keeping with the view that hypnosis involves the dissociation of prefrontal cortex from other neural functions.

Topographical analysis of stimulus-related and response-related electrical scalp activity and interhemispheric dynamics in normal humans.

It is believed that reaction time estimates of interhemispheric relay (IHR) time or accuracy cost reflect motor relay and that visual evoked response potential (ERP) estimates reflect visual relay. If this is so, then response-related ERP estimates of IHR might be expected to correlate more with reaction time (RT) estimates of IHR than visual ERPs do, and the former ought to interact with the latter. A simple reaction time experiment (Poffenberger paradigm) was carried out with an 18-electrode montage on 10 normal subjects to investigate visual and motor interhemispheric relay effects and their interrelation. Three components in stimulus-synchronized and three other components in response-synchronized averaged signals were analyzed. Latencies and amplitudes of these components were studied as a function of the visual field stimulated and the hand required to respond. Effects interpretable as interhemispheric relay effects were observed in stimulus-related as well as response-related components. Few interhemispheric relay effect estimates in stimulus-related and response-related electrical scalp potentials were related to behavioral estimates of interhemispheric relay effects (derived from reaction times and omission errors). The spatiotemporal distributions of the electrical interhemispheric relay effects differed in stimulus and response-related components and they were statistically unrelated. We conclude that sensory interhemispheric relay may be picked up with stimulus-synchronized ERPs whereas motor interhemispheric relay effects may be measurable with response-related ERPs in normal humans. However, this proposal ought to be tested with callosotomized subjects.

Impairment in frontal but not temporal components of mismatch negativity in schizophrenia.

Impairment in mismatch negativity (MMN) potentials is a robust finding in schizophrenia. While previous studies suggested that MMN in man is generated by a single dipole source bilaterally in the primary auditory cortex, more recent data modified this assumption by showing differential modulation of MMN components over the frontal and temporal scalp. Here we used a roving standard experiment to record mismatch potentials to tone duration deviants with the aim to detect robust temporal and frontal mismatch components. Fourteen schizophrenic patients with normal intelligence and without overt cognitive deficits and age- and sex-matched controls were studied. In agreement with previous findings MMN recorded from the frontal scalp was markedly attenuated in patients. However, in contrast to previous reports, positive mismatch potentials of normal magnitude were recorded from temporal (mastoid) electrodes. This finding raises the possibility of a selective impairment in multiple mismatch generators in schizophrenia and may lend support for the notion of impaired cortico-cortical connectivity in schizophrenia.

Paradox lost? Exploring the role of alpha oscillations during externally vs. internally directed attention and the implications for idling and inhibition hypotheses.

Although slow waves of the electroencephalogram (EEG) have been associated with attentional processes, the functional significance of the alpha component in the EEG (8.1-12 Hz) remains uncertain. Conventionally, synchronisation in the alpha frequency range is taken to be a marker of cognitive inactivity, i.e. 'cortical idling'. However, it has been suggested that alpha may index the active inhibition of sensory information during internally directed attentional tasks such as mental imagery. More recently, this idea has been amended to encompass the notion of alpha synchronisation as a means of inhibition of non-task relevant cortical areas irrespective of the direction of attention. Here we test the adequacy of the one idling and two inhibition hypotheses about alpha. In two experiments we investigated the relation between alpha and internally vs. externally directed attention using mental imagery vs. sensory-intake paradigms. Results from both experiments showed a clear relationship between alpha and both attentional factors and increased task demands. At various scalp sites alpha amplitudes were greater during internally directed attention and during increased load, results incompatible with alpha reflecting cortical idling and more in keeping with suggestions of active inhibition necessary for internally driven mental operations.